Indicating instrument



May 9, 1950 v G. F. MERTL ETAL 2,507,115

INDICATING INSTRUMENT Filed March 24, 194 2 Sheets-Sheet 1 Patented May9, 1950 PATsEN T [CE INDICATING INSTRUIVIENT Glen,.=1". .,-Mentl.,alndRudolf Kndnanmc m; 111,, assignorsto Stewart-Warner Corporation,Chicage, 111., ,a corporation of Virginia Application-:March -24,1948,7S1erial Np. 1,617.08

"1 lQlaim.

The; present invention relates to. indicating intruments ,such as;speedometers ,for automotive .vehicles, -.and more, particularly to animproved indicating; means which is more 4 readilyrobservable andwhichincludes means. in; additionsto the --conventional scale for -.giving areading.

"The conventional .sneedometer I or other -indi- Gatinginstrument isequipped with a scale,-andva pointer forming an index which registers.on .this scale. These; instrumentsoften-are hard;to-read, particularly:under p091: lightingconditions. The present invention. is designed to:overcome this ;disandvantag e 10f conventional instruments by means. ofa new] form-of speed. indicator cooperating with visible meansimaddition to the i con- ;ventional indieiaor-scalefor; givingianindication ofspeed.

.Aceording-ly it? is an Qbject,= of v the; invention, to {provide anindicating, instrument havin a: new and improved indicator memberafar-facilitating reading; of the instrument.

Another object ofgthe inventionistheprovision of a new and improvedindicating instrument vwhich; incorporatesmeans-in addition to the. coneventional scale 'forrgiving auvisual indication or reading.

A further object of :the invention ;is :the provision of :a new. andimprovediindicating instrument which includes.a-fixedscale andindicatormembers, one of. whichearriesian index for, registering onrthe scaleand,isdisposed inroverlying relation to the oth-erz-member; whichmembersaare relatively movableto; give; a reading indicated byregistration of the index on the scale andibythe portion .of, theunderlyin member ex-posed to View. A bandof color. contrast-ing:. withthezcoior oftheeindioati-ng inembersapreferably'is provided on theunderlying member-ate facilitate observationof the part thereofexposedtol-view.

A still further objectof thezinvention isrthe provision of an improvedindicatinginstrument as above setiforthi in which the indicator-membersconform in shape to a helixtof'?less;than: 360i degrees in extent andthe overlying member iSzlT-IOV- ableand hasan-endwhich forms'the index.

A more specific objectof theinvention is the provision of animprovedindicatin instrument as above set forth inwh-ich the indicatormembers conform in shape toahelix ofl-ess-than 360 -de- 'grees but morethem-I80 degrees inextent and the overlying member is rotatable and isprovided with means *for moving the same axially upon rotation an amountapproximating the lead of the indicator' members over :the dlstancetherotatable-mem'ber iS'IOliaiSQd 'SWUhat" th Iea'dingend of .thet-rotatable member will :be disposed under the end; of thefixed membertoward whiohzit 11S advanced and: thus the entire length. of the.

sivein construction and, therefore, easyto-in-stafl and; does notget-out of order easily.

,lhese and other: objects of 'the invention will become apparent fromthen-following. description, wherein reference is ,had to =.theaccompanying drawings, in which:

:Fig. lflis a vfrontelevational 1 View. of an, indieatlinginstrumentconstructed in accordance with the principles of the; presentinvention with. a portion ofthe face: plate broken: away to showtimeiindicatorzmembers in: plan;

Fig. 2 is.- a front elevational view similar torEig. .1 but with'theti-ndicating members moved ;to an indicating position;

3.is a tvertical diametrical sectional taken; ,on the line.33 of! Fig: 1rand .='Eig.-4 is a fragmentary sectional view taken :oni thelinex4-4 ofFig. 3.

order-tot illustrate the-principles of .thepresent invention. it :has:beenshown and wil-l'rbe de- :seribed --asapplied1,-to a speedometer:for motor ears or trucks; but it! is to bez understoodnthatzthe-:princip1es 'zarer-applicable to 7013118!" types :of indiccaitinginstruments in addition to speedometers- For :the purpose-. ofillustration amechanically -,1),perated speedometer is. shown enclosed\within za'generally ball shaped housing it (Big; 3) which mayaberformedasasheet metal stamping. housingcomprises .a a rear cup shaped part5: I2 of reduced diameter for housingthe operatingtparts of {the speedometerand a part M of enlargeddiameter for housing' the indieator:members andthe ;s1lp.p0rts-rtherefor. The peripheral edgeeof the enlarged part: of."the 'housing isbentloutwardlyitoiform a flange lafi for apurpose-whiten will "befrleseri'bed subsequently, and the reduoedeupshapedmart I Zhas: a back wall l=8.

Supported upon the. back wall it of the housing byanysuitable'means is abody casting '2 llwhich supports-the-operating parts of theispeedometer.Since these; parts may be of conventional construction andform no "partof the invention-a dctaileddisclosure thereof isnotthollght to benecessary. Ina conventional speedometer o'fjthis type a'speed enp'lsrotatably secnred in th'eaStingfonrotating a movable? indicator-memberand this speed cup is rotated by magnetic forces acting thereon, whichare produced by a rotatable cylindrical magnet. This magnet is driven bya shaft 22 projecting from the rear end of a rearwardly projectingextension 24 on the body casting. The shaft is separably connected bysuitable means to a part of the vehicle transmission or any otherrotating part of the Vehicle which rotates in a constant predeterminedspeed relationship to the wheels of the vehicle in which the speedometeris mounted.

At its front end the body casting is formed with forwardly projectingbracket arms 26 and 28 adapted to support the speed indicating means andthe odometer unit of the speedometer. This latter unit is not shownbecause it may be of conventional construction. Normally, it would besupported between the bracket arms 26 and 28 adjacent their forward endsand would be driven from the shaft 22 by conventional driving mechanism. Such a driving mechanism includes a cross shaft 30 having a worm32 fixed thereon which engages a pinion fixed on the rear end of a shaft34 extending longitudinally of the housing and suitably supported uponthe body casting for rotational movement. At its forward end the shaft34 carries a worm 36 which engages with a pinion 38 rotatably supportedon the outer side of the bracket arm 28 and fixed to drive a secondpinion 40 disposed on the inner side of :1;

the bracket arm. When the shaft 22 is rotated as a result of movement ofthe vehicle, the pinion 40 is rotated through the gear train abovedescribed and drives the odometer unit for indicating total mileage.

Also supported upon the forward end of the bracket arms 26 and 28 is ajewel supporting bracket 42 which is secured as by screws 44 tolaterally projecting lugs 46 on the front ends of the bracket arms. Thejewel bracket 42 may be formed from a sheet metal strap as indicated inFigs. 3 and 4 and it is preferably upwardly stepped intermediate itsends to provide a depressed central portion 48 and separate planeportions 50 spaced above the central portion which are secured to thelugs 48 on the bracket arms 26 and 28 for holding the jewel bracket inplace as previously mentioned. The outer extremities 52 of the jewelbracket lie in a common plane elevated above the portions 50 and formsupports for the stationary part of the speed indieating mechanism whichcomprises a dial plate 54 that forms one of the novel features of thepresent invention, as will appear hereinafter.

A speed indicator shaft 56 which is fixed to the speed cup previouslymentioned is supported adjacent its forward or outer end in a jewelbearing 58 carried in the intermediate part of the depressed portion 48of the jewel bracket. Adjacent its opposite end this shaft is supportedwithin the confines of the speed cup by a second jewel bearing (notshown) carried in a bracket 60 having an arm depending from the forwardend of the casting into the speed cup. These bearings may be of a knowntype and the outer bearing 58 is shown supported in a socket formed in abearing cup 62 carried by the jewel bracket 42.

Rotational movement of the speed indicator shaft 56 from itspredetermined zero position is resisted by a tensioned spiral hairspring 64 having its inner end secured to the shaft. The outer end ofthe spring is fixed to an arm on an adjustable spring adjuster 66supported upon the intermediate portion 48 ofthe jewel bracket. Thisadjuster is rotatable relative to the speed indicator shaft so that thetorque applied to the 4 shaft 56 by the spring can be adjusted to insureaccurate functioning of the speedometer and return of the shaft to itszero position. Releasable means such as a nut 68 is provided for lockingthe adjuster in position after the spring 64 has been properlytensioned.

The speed indicating means forming a novel feature of the presentinvention includes the fixed dial member 54 previously mentioned, and amovable speed indicator 70 which is rotated by the speed indicator shaftthrough means presently to be described. The fixed dial member 54 may bea sheet metal stamping having a configuration defining the major portionof an annulus. Radially extending edges 12 and 14 form the opposite endsof this dial member and define an open space behind which the odometerunit of the speedometer may be secured. From end to end the body of thedial member 54 is formed with a slight helical curve or pitch, and atdiametrically opposite points on the periphery a pair of supportingbrackets '56 are formed as shown in Figs. 2 and 3. These brackets aresecured to the end portion 52 of the jewel bracket by means of screws13, a washer 88 being interposed between the brackets and the endportions 52. It will be noted in Fig. 3 that the left side of the dialmember is supported in a plane elevated above the right side because ofthe helical curvature in the body of the dial member.

Cooperating with this fixed dial member 54 is the speed indicator itwhich like the dial member has a configuration defining the majorportion of an annulus of somewhat smaller diameter than the dial memberas best seen in Fig. 2. The speed indicator has radially extending ends82 and 84 and is curved from end to end to correspond with the curvaturein the body of the dial member. Integrally formed with the annular partof the speed indicator I0 is a central disc-shaped part 88 connected tothe annular part by a rib 88. The upper end of a worm 98 is received inan aperture in the disc and the parts are fixed with respect to eachother by curling over the end of the worm, as indicated at 92 in Fig. 3.The disc and worm thus form a hub for the speed indicator which isoperatively connected to the speed indicator shaft 56 for rotationalmovement therewith and axial movement relative thereto by means whichwill now be described.

Referring to Fig. 3, it will be seen that the speed indicator shaft 55carries bushing 84 press fitted or otherwise suitably secured on itsouter end.

The speed indicator assembly comprising the annular speed indicator andworm are loosely received over the bushing and are fixed againstrotation relative thereto by radially extending pins 96 in the wormhaving inner ends loosely received in axially extending slots 98 in theperiphery of the bushing so that the speed indicator assembly is movableaxially of the speed indicator shaft while it is being rotated by thelatter.

Axial movement is imparted to this assembly by cam means which includesthe worm and a stationary pin H30 engaged with the worm and fixed to abracket [E12 secured to the bracket arm 26 on the body casting inoverlying relation to the jewel bracket by means of the screw 44.Rotation of the speed indicator shaft from the zero position results inthe speed indicator assembly being drawn downwardly by this cam meansand in its being raised when the speed indicator assembly is returned tothe zero position.

In order to protect the operating parts just 5 described, the open frontend of the housing is closed by a transparent dial plate [E34 whichrests upon an annular ridge 6% adjacent the periphery of a cup-shapedfacing member E08. This member has a peripheral flange Iii! whichengages upon the flange it on the enlarged part of the housing. Thesemembers are fixed in position by a cylindrical bezel member i I 2 havinga side wall H4 with a peripheral flange lit formed thereon which engagesupon the flange I iii on the facing member m8. The peripheral edges ofthe flange H6 on the bezel member are turned over the back side of theflange it on the housing to hold the parts in assembled relation asshown in Fig. 3. A circular sight opening lit is defined by the innerperiphery of the bezel member i i 2 and this periphery is generallychannel-shaped in crosssection to provide an outwardly directed flangeI20 for engaging the transparent plate Hi4. In

the assembled instrument, the plate [94 is firmly clamped between theannular ridge lot and the flange I20.

As indicated in Figs. 1 and 3, the facing member I08 has a circularopening E22 through which the fixed dial member 54 and the speedindicator 1B are visible, and along the periphery of this opening ascale is provided consisting of numbers as shown ranging in tens fromzero to 100, for example, to indicate speed in miles per hour.

In assembling the instrument, the fixed dial member 54 is secured withits radial end 72 registering with the Zero mark on the scale while theother end i l may register with the highest mark on the scale. Likewisethe speed indicator I is set with its radial end 52 registering with thezero on the scale so that in this position the speed indicator masks thedial member 54, and the end 82 of the indicator member forms an indexfor registering on the scale.

Upon rotation of the speed indicator shaft the speed indicator ii! isrotated and exposes a portion of the fixed dial member 54, the portionexposed being proportional to the speed at which the vehicle istraveling. Thus a visual indication of this speed is given not only bythe registration of the index edge 82 on the scale, but also by theportion of the dial member 54 which is exposed. To facilitateobservation the fixed dial member a is provided with a band I24 ofcontrasting color (Fig. 2) extending from end to end thereof.

As the speed indicator i0 is rotated, the pin I00 engaged with the Worm9!! draws the Worm and speed indicator downwardly on the bushing 94 anamount approximately the lead of this helically formed indicator memberso that the leading end 84 of the indicator is lowered below the planeof the end 12 of the fixed dial member 54 and passes under this memberas indicated in Fig. 2. Thus the uncovered portion of the band I24remains visible irrespective of how far the indicator is rotated withoutthere being any danger of the indicator wedging against the dial.

It will be apparent that the principles of the invention as applied tothe speedometer described above are readily applicable to other forms ofindicating instruments, and while the fixed and movable indicatormembers have been shown and described as annular, certain of theprinciples of the invention could be applied to instruments havingindicator members of other shapes. It will also be apparent that othermodifications and variations of the preferred embodiment of theinvention described above can be made without departing from theunderlying principles of the invention. We, therefore, desire by thefollowing claim to include within the scope of the invention all suchvariations and modifications by which substantially the results of ourinvention may be obtained through the use of substantially the same orequivalent means.

We claim:

In an indicating instrument, indicating means including fixed androtatable members each conforming in shape to a helix of less than 360degrees in extent, said members being disposed in overlying relation oneWith respect to the other, means for rotating and axially moving saidrotatable member to cover or expose a portion of the underlying memberin proportion to the magnitude of the quantity being measured includinga rotatable shaft, means for rotating said shaft in proportion to themagnitude of the quantity being measured, means journaling said shaftfor rotation but inhibiting said shaft against endwise displacement, aworm secured to said rotatable member, said worm having substantiallythe same pitch and direction as said rotatable member, a fixed wormfollower engaged with said worm to axially advance or retract said wormand rotatable member as said rotatable member is rotated, and meanssplining said rotatable shaft to said worm so as to rotate said shaftand worm together while not inhibiting axial displacement of said wormand rotatable member relative to said shaft.

GLEN RMERTL. RUDOLF KN OTHE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 201,637 Treat Mar. 26, 18781,468,235 Japy Sept. 18, 1923 2,011,517 Geofirion Aug. 13, 19352,255,188 Rieper Sept. 9, 1941

